Niobium

You might not care about the Infernus since you can easily get a Turismo at that car dealership in Algonquin anyway, but if you want an Infernus, this tutorial should help.

1. Go to your phone and select Stubbs>Job

2. Stubbs might give you the mission where you plant the bug on Bryce Dawkins' car. If he gives you a different mission, complete that mission and go back to step 1. If he gives you the mission with the bug on Bryce Dawkins' car, continue to step 3.

3. After Stubbs tells you to steal Dawkins' Infernus, drive all the way to the Infernus like the mission instructs you to do.

4. Get in the Infernus. The game will instruct you to drive the Infernus over to that bug-planting guy by 20:30, or 12:45 or whatever. DO NOT drive to the bug-planting guy. Instead, drive the Infernus to your safehouse. Park the car in the parking space.

5. Exit the car, and hijack another car from the streets. Drive away from the safehouse so you can't see it anymore. Then, fail the mission by passing the time limit, which was 20:30, or 12:45 or whatever.

6. Once you go over the time limit, Johnny will call Stubbs to say he failed to deliver the car or whatever. After the call, drive back to the safehouse where you parked your Infernus.

7. You now have an Infernus that you can drive around!

If you have any questions, you can post them here and I will try to help you. Hopefully this tutorial helps.